Basel, Switzerland, 6 November 2011 | AFP

Japan’s Kei Nishikori stunned Novak Djokovic 2-6 7-6 6-0 on Saturday to hand the world No.1 only his fourth loss of the season with a semi-final defeat at the Swiss Indoors.

Djokovic was suffering with a shoulder injury which he said had been getting worse all week as he returned to tennis here after six weeks away with a back problem’

Nishikori, ranked 32nd in the world and a semi-finalist last month at the Shanghai Masters, will play one of two Swiss players, four-time champion Roger Federer or Stanislas Wawrinka for the title.

Djokovic said he in unsure if he will be fit to play the final regular event of the ATP season, the Paris Masters starting on Monday.

“I don’t think I’ll be able to train for the next few days,” said the top seed and winner of ten titles this year. “But I think I’ll go straight to Paris.”

The shoulder injury, which was treated twice during the match, was similar to one which forced Djokovic to quit his final in August at Cincinnati against Andy Murray.